Step attachment for a dental stool

ABSTRACT

The step attachment comprises a plate member adapted to extend radially from the center post of a dental stool in an overlying relation with the stool base, which carries floor engaging caster wheels. The plate member is movably supported at the lower end of the post for rotational movement about the post and for pivotal up and down movement of its outer end. A leg member at the outer end of the plate member is normally yieldably held out of engagement with the floor whereby the stool is freely movable along the floor and the plate member fully rotatable about the post. When the plate member is stepped on the leg member is moved into bearing engagement with the floor to hold the stool against floor movement.

United States Patent 1191 F ortnam '[4 June 28, 1974 [75] Inventor: George A. Fortnam, Des Moines,

Iowa

[73] Assignee: Den-Tal-Ez Mfg. Co., West Des Moines, Iowa 221 Filed: Apr. 30, 1973 211 Appl. No.: 355,764

l/l96l MacKnight 297/240 Primary ExaminerCasmir A. Nunberg Attorney, Agent, or Firm-Rudolph L. Lowell [57] ABSTRACT The step attachment comprises a plate member adapted to extend radially from the center post of a dental stool in an overlying relation with the stool base, which carries floor engaging caster wheels. The plate member is movably supported at the lower end of the post for rotational movement about the post and for pivotal up and down movement of its outer end. A leg member at the outer end of the plate member is normally yieldably held out of engagement with the floor whereby the stool is freely movable along the floor and the plate member fully rotatable about the post. When the plate member is stepped on the leg member is moved into bearing engagement with the floor to hold the stool against floor movement.

4 Claims, 6 Drawing Figures SUMMARY OF THE INVENTION The step attachment is of a simple construction and efficient in operation to provide a convenient stool step down for a dental assistant concurrently with a locking or braking of the stool against floor movement. Slipping of the stool outwardly from under the dental assistant when demounting from, or mounting, the stool and resultant possible injury is thus positively prevented. Additionally, when the stool is in use the assistant need only rest the feet on the step to lock the chair on the floor against free wheeling. The attachment is readily adaptable to many type dental stools now in use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a dental stool showing the step attachment in assembly relation therewith;

FIG. 2 is an enlarged partial sectional view taken on line 22 in FIG. 1;

FIG. 3 is a sectional view on line 33 inv FIG. 2;

FIG. 4 is an enlarged sectional detail view as seen on line 44 in FIG. 3;

FIG. 5 is an enlarged sectional detail view on line 5-5 in FIG. 4; and I FIG. 6 is an exploded perspective view of a ring assembly which movably supports the step attachment for horizontal rotational movement and for pivotal up and down movement relative to the center post of the stool.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, there is shown in FIG. 1 a usual type stool 10 for a dental assistant. The stool includes a base 11 for an upright center post or standard 12 which carries at its upper end a seat unit 13 equipped wth a back rest 14. The base (FIGS. 1 and 2) includes a central hub section 16 from which radially extends a series of feet members 17, illustrated as four in number, arranged indiametrically opposed pairs. Supported from the free or outer end of each foot member 17 is a floor engageable caster wheel 18. A foot rest 19 for the dental assistant or stool user is of a ring shape positioned concentrically relative to the hub section 16 and secured to the upper surface of the feet members 17 adjacent the free ends thereof.

The central hub section 16 is of cylindrical tubular shape and constitutes a lower end section for the center post 12. The post has an upper end section 22 of a rod form that is telescopically received within the post lower section 16. An adjusted moved position of the upper post section 22 is maintained by a usual friction or clamping screw23 which is threadable within the lower post section 16 and into engagement with the upper post section 22.

The step attachment of this invention, generally indicated at 24, (FIGS. 2 and 3) includes a flat step or plate member 26 which extends radially outwardly from the center post 12 in a substantially horizontal position overlying the base 11. The plate member 26 is of a generally rectangular shape and is formed with an inner end section 27which terminates in a central longitudinal extension having a semicircular notch 28 to form a pair of transversely spaced arm members 29 (FIGS. 2 and 4) positioned in a straddling relation with the lower end section 16 of the center post 12. The free ends of the arms have horizontally extended axially aligned tapped holes 30. The outer end section 31 of the plate member 26 projects outwardly from the base 11 for a purpose to appear later.

The plate member 26 is movably supported for rotational movement relative to the vertical axis of the center post 12 and for up and down pivotal movement of its outer end 31 about a horizontal axis extended through the holes 30 of the spaced arm member 29. These movements of the plate member 26 are accomplished by the provision of a ring assembly, indicated generally as 32, (FIGS. 4 and 6) which includes a mounting ring 33 and a rotatable ring 34. The mounting ring 33 is of a split type having the half sections thereof connected together by connecting screws 36. The assembled mounting ring 33 is rigidly secured about the lower post section 16 by clamping screws 37 threadable radially of the ring 33 and into engagement with the outer peripheral surface of the center post section 16.

The outer peripheral surface of the mounting ring 33 is formed with a circumferential groove 38 of a size to rotatably receive therein the rotatable ring34. Similarly to the mounting ring 33, the rotatable ring 34 is of a split type so as to provide half sections 39, each of which is formed with a radially extended hole 41 located centrally between the ends thereof. With the ring half sections 39 positioned within the groove 38 the spaced arms 29, at the inner end 27 of the plate member 26, are arranged at opposite sides of the central post 12 to a position wherein the holes 30 at the free ends thereof are in axial alignment with the holes 41 in the'rotatable ring 34. Pivot pins 42, commonly known as half dog point set screws are threadable within the arm holes 30 (FIGS. 3 and 5) for extension of their shank sections 43 within theholes 41 of the rotatable ring 34. By virtue of this assembly, the half sections 39 of the rotatable ring 34 are maintained against separation concurrently with pivotally supportingthe plate member 26 on the pivot pins 42. It will be noted also that the semicircular notch 28 provides a working clearance of the step member with the post section 16 during up and down pivotal movement thereof. Plastic spacers 44 (FIG. 4) secured to the end faces of a halfsection 39 of the rotatable ring 34 compensates for the material cut away in the forming of such sections.

The plate member 26 is yieldably urged to an upper pivotally moved position, indicated in dotted lines in FIG. 3, by means of a Hat spring 45 having one end 46 secured to the underside of' the inner end 27 of the plate member and its other end 47 resting in slidable contact engagement on the top surface of the ring shape foot rest 19. In this upper pivotally moved position of the plate member a pair of leg members 48 projected downwardly from its outer end 31 at a position outwardly from the base 11 are elevated so as to be in a clearance relation with a floor surface indicated at 49. In the upper pivotally moved position, therefore, the plate member 26 is freely rotatable about the vertical axis of the central post 12 in a supported position on the foot rest 19. I-Iowevenwhen pressure is applied downwardly on the plate member, as occurs when it is stepped on by a person to be seated on or leaving the stool, the lower ends of the legs 48 are moved downwardly against the pressure of the spring 45 into bearing engagement with the floor 49, as shown in full lines in FIG. 3. The stool 10 is thus locked against free wheeling movement on the caster wheels 18. In this re- 3 spect it is to be noted that a Similar locking action is obtained when the stool user is seated withthe feet supported on theplate member 26. g

It is seen, therefore, that the stool l is'locked against free floor movementwhen in use, and during the seating and unseating of a person such as a dental assistant. As a result, any injury or damage that may result by the tendency of the stool being pushed away by a person in mounting on or demounting from the stool is corripletely eliminated. Likewise, any accidental floor movement of the stool when in use is also eliminated.

Although the'invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes and modifications can be made therein which are within the full intended scope .of this invention as defined by the appended claims.

I claim:

1. A step attachment for a dental stool having a vertical standard mounted on a base provided with floor engaging caster wheels; said attachment comprising:

a. a substantially horizontal plate overlying said base having an inner end portion adjacent said vertical standard, and an outer end wardly from said base,

b. a floor engaging leg means secured to and projected downwardly from said outer plate portion, 0. means movably supporting the inner. end of said plate member on said vertical standard for rotational movement of the plate about the vertical axis of said standard, and for up and down pivotal movementof said outer portion about a horizontal axis extended transversely 'of said vertical axis, and d. coacting means on said base-and on said plate for yieldably urging said plate to' an upper pivotally portion projected outmoved position wherein said leg means are in a clearance relation with the floor, 1 I e. saidleg means,'when said plate is stepped upon, being movable into bearing engagementwith the floor surface to rigidly support-the plateagainst downward pivotalmovement and to lock-v said stool against floor movement. i I 2. The step down attachment for a dental stool according to claim l wherein:

a. said base includes a plurality of feet members extended radially from said vertical standard, and I b. said coacting means includes a ring member con centric with said vertical-axis-supported on and secured to the upper surfaces of saidfeet members, and i I c. a spring member secured to the under side of said plate in slidable contact. engagement with the upper surface of said ring member.

3. The step down attachment for a dental stool according to claim 1 wherein:

a. said supporting means includes a rotatable ring member positioned about the lower end of said standard and rotatable about said vertical axis, b. a pair of transversely spaced arm members projected longitudinally outwardly from the inner end portion of said plate to opposite sides of said rotatable ring, and

-c. pivot means pivotally connecting said arm members on said rotatable ring at positions equidistant from said vertical axis to provide for the pivotal movement of said plate about said horizontal axis.

4. The step down attachment for adental stool according to claim2 wherein: 1

a. said leg means includes a pairof leg members spaced transversely of said plate member. 

1. A step attachment for a dental stool having a vertical standard mounted on a base provided with floor engaging caster wheels; said attachment comprising: a. a substantially horizontal plate overlying said base having an inner end portion adjacent said vertical standard, and an outer end portion projected outwardly from said base, b. a floor engaging leg means secured to and projected downwardly from said outer plate portion, c. means movably supporting the inner end of said plate member on said vertical standard for rotational movement of the plate about the vertical axis of said standard, and for up and down pivotal movement of said outer portion about a horizontal axis extended transversely of said vertical axis, and d. coacting means on said base and on said plate for yieldably urging said plate to an upper pivotally moved position wherein said leg means are in a clearance relation with the floor, e. said leg means, when said plate is stepped upon, being movable into bearing engagement with the floor surface to rigidly support the plate against downward pivotal movement and to lock said stool against floor movement.
 2. The step down attachment for a dental stool according to claim 1 wherein: a. said base includes a plurality of feet members extended radially from said vertical standard, and b. said coacting means includes a ring member concentric with said vertical axis supported on and secured to the upper surfaces of said feet members, and c. a spring member secured to the under side of said plate in slidable contact engagement with the upper surface of said ring member.
 3. The step down attachment for a dental stool according to claim 1 wherein: a. said supporting means includes a rotatable ring member positioned about the lower end of said standard and rotatable about said vertical axis, b. a pair of transversely spaced arm members projected longitudinally outwardly from the inner end portion of said plate to opposite sides of said rotatable ring, and c. pivot means pivotally connecting said arm members on said rotatable ring at positions equidistant from said vertical axis to provide for the pivotal movement of said plate about said horizontal axis.
 4. The step down attachment for a dental stool according to claim 2 wherein: a. said leg means includes a pair of leg members spaced transversely of said plate member. 